Robust Targets Coverage for Energy Harvesting Wireless Sensor Networks

Energy harvesting wireless sensor networks (EH-WSNs) form the foundation of Internet of Things (IoTs) systems. Energy harvesting nodes can be deployed strategically to monitor one or more targets such as a valuable asset. However, as these nodes rely on ambient energy sources such as solar, they experience random energy arrivals. Consequently, they may exhaust their harvested energy while monitoring a target. Therefore, network operators require a <italic>robust</italic> solution that ensures all targets are monitored continuously over some time period with a given probability. In this paper, we consider three novel robust coverage requirements; each must hold with probability (<inline-formula><tex-math notation="LaTeX">$1-\epsilon$</tex-math></inline-formula>), where <inline-formula><tex-math notation="LaTeX">$\epsilon$</tex-math></inline-formula> is the probability of failures. First, sensor nodes must not expend more than their <italic>total</italic> harvested energy over <inline-formula><tex-math notation="LaTeX">$T$</tex-math></inline-formula> time slots. Second, the energy expenditure of each sensor node must not exceed the energy harvested in <italic>each slot</italic>. Third, the energy expenditure of sensor nodes must not exceed the energy accumulated up to the current slot. We formulate chance-constrained stochastic programs that incorporate these requirements and solve them using the sample average approximation method. We confirm via extensive simulation studies that our programs are capable of computing sensor nodes activation times that meet a given coverage failure probability.